In recent years, aqueous suspension formulations referred to as “flowable” have been becoming mainstream of agrichemical formulations for foliar application. A main reason for this is that aqueous suspension formulations cause no generation of dust and thus cause little worker exposure to dust, while formulations such as wettable powders and dust formulations easily cause worker exposure to dust.
On the other hand, the persistence of the effect of a fungicidal active ingredient often decreases during the period of foliar application. Possible causes for this include dilution of the active ingredient on phylloplane with the growth of plants, photodecomposition on the phylloplane, and wash-off of the fungicidal active ingredient from the phylloplane due to rainfall. A non-systemic fungicide easily undergoes a decrease in residual effectiveness due to rainfall because the applied active compound remains on the phylloplane without penetrating and transferring into a plant. In order to maintain a predetermined fungicidal effect, therefore, an excess of agrichemical is applied to impose much labor and economical load on a worker, thereby causing environmental contamination.
It is known that a fungicidal active ingredient, (RS)-N-[2-(1,3-dimethylbutyl)thiophene-3-yl]-1-methyl-3-trifluoromethyl-1H-pyrazole-4-carboxamide, used in the present invention exhibits an excellent effect on a wide variety of diseases (European Unexamined Patent Application publication No. 0737682).
This active compound is water-insoluble and has a high melting point, and an aqueous suspension formulation has been studied for using the compound for foliar application. However, there is known only an aqueous suspension formulation produced by wet-grinding the compound in water simply using a surfactant according to a general formula. In application of a liquid medicine containing the compound involved in the present invention to crops, the persistency of the effect significantly decreased by rainfall thereafter.
In recent, various means for preventing a decrease in the agrichemical effect due to rainfall have been studied. For example, Japanese Unexamined Patent Application Publication No. S54-80423 discloses agrichemical coating agents containing α-starch and thus having high rain resistance. Japanese Unexamined Patent Application Publication No. S59-172401 discloses wettable powders containing a powdery resin added for improving rain resistance. Japanese Unexamined Patent Application Publication No. H02-40301 discloses water-dispersible granules containing polyvinyl alcohol or carboxymethyl cellulose added for improving rain resistance by enhancing sticking tendency. Patent Application WO97/46092 discloses emulsions, aqueous suspo emulsions, wettable powders, suspensions, and water-dispersible granules each containing sorbitan trioleate added for improving rain resistance.
However, when any one of the materials described in the above-described documents or a commercially available general spreading agent functioning as an adjuvant was used for the fungicidal active ingredient of the present invention, no material was found for preventing (improving rain resistance) a decrease in the persistence of the effect of the compound due to rainfall.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. S54-80423
[Patent Document 2] Japanese Unexamined Patent Application Publication No. S59-172401
[Patent Document 3] Japanese Unexamined Patent Application Publication No. H02-40301
[Patent Document 4] Patent Application WO97/46092
[Patent Document 5] European Unexamined Patent Application publication No. 0737682